Apparatus fob purifying plating



July 27, 1937. R H, TULL 2,088,498

APPARATUS FOR PURIFYING PLATING SOLUTIONS s Filed OCL. 9,l '1956 Patented July 27, 1937 2,088,498L ,t

- UNITED STATES PATENT ori-lcs APPARATUS FOR. PURIFYING PLATING SOLUTIONS Robert H. Tull, East Springfield, Mass., assignor to Westinghouse Electric & Manufacturing Company, East Pittsburgh, Pa., a corporation of Pennsylvania q Application October 9, 1936, SerialNo. 104,910 8 Claims. `(Cl. 204-5) This invention relates to apparatus ,for purify- In 'order to return the plating solution to the ing plating solutions. plating tank I2, suitable. outlet pipas 28 and 30 In plating surfaces with a covering of metal, are disposed in settling tanks I4 and I6, respecthe plating solution employed becomes saturated tively, and are connected to a return pipe.32

through which the plating solution ows to the t of the plating solution. 'I'hese impurities so inplating tank I2. l terfere with the plating process that they must'I Valves 3d and 36 are disposed in the inlet pipe be removed or the solution must be discarded. I8 and outlet pipe 28, respectively, of the settling In the apparatus employed heretofore for retank I I and valves 38 and I0 are disposed in the l claiming the plating solutions, it was necessary inlet pipe 20 and the outlet pipe 30, respective- 10 to stop the purifying operation and clean the ly, of the settling tank I6 for controlling the flow apparatus to remove the impurities therefrom. of the plating solution to and from the settling Where such an apparatus is employed, the extanks 0r for isolating either of the settling tanks pense incurred by interrupting the purifying from the circulating system as will be explained process to clean the-apparatus renders the apmore fully hereinafter. 15 paratus undesirable. In order to insure a positive flow of the plating An object of this invention is the provision of Solution from the settling tanks when either apparatus for eiecting the continuous removal valve 36 or tu is opened, a liquid Dump 42 Simof impurities from plating solutions. ilar to liquid pump 2d is disposed in the return Y Another object of this invention is the propipe 32 of the circulating system between the out- 20 vision of apparatus for removing impurities from let pipes 2B and 30 and the Plating tank l2 t0 plating solutions whereby the apparatus maybe fOrCe the Plating SOllltiOn under pressure t0 the cleaned without interrupting the .removal of plating tank. The liquid Pump 62 1S disposed t0' impurities from the solution. be actuated by means of a suitable motor M Other objects will become apparent from the which is connected to a suitable source of power 25 following description when taken in conjunction (not shown), and may be energized for operwith the accompanying drawing, the single ligure ation, as desired. of which is a diagrammatic view of the apparatus Since the impurities formed in the plating S0- embodying the teachings of this invention. lution during the plating operation are usually As illustrated in the accompanying drawing, of the type whereby they will crystallize and 30 the apparatus for removing the impurities from a settle out ofthe solution when the temperature plating solution comprises a circulating system of the solution is lowered to a predetermined I0 connected to a plating tank I2 which convalue, refrigeratmg means t6 and 48 are assotains a suitable plating solution (not shown) for ciated with settling tanks I c and I6, respective'- the circulation of the plating solution from and ly, for effecting a reductionin temperature of the 35 to the plating tank. solution or liquid contained in the settling tanks.

l In order to remove the impurities from the The refrigerating apparatus 46 and 48 may be oi plating solution as it ows through the circulatany suitable type and may be operated simuling system I0, a plurality of settling tanks I 4 and taneOllSly 0r Separately, as desired.- It is to be I6 are provided associated with the circulating preferred that the refrigeratiilg apparatus be 40 system. The settling tanks IB and I6 are conmaintained out of contact with the solution in nected by means of the inlet pipes I8 and 20, rethe settling tanks.

spectively, to a supply pipe 22 through which As illustrated in the drawing, the supply pipe the plating solution ows from the plating tank 22 passes through the return pipe 32 to provide i5 I2 to the respective settling tanks. a heat exchanger. This is desired since the plat- 45 In order to insure a positive ilow of the plating ing solution withdrawn from the plating tank I2 solution from the plating tank I2 to the settling is usually' warm, whereas the plating solution tanks, a liquid pump 24 is disposed associated withdrawn from the settling tanks is too cool to with the circulating system to force the plating supply directly to the plating tank I2. By pro- 0 solution from the plating tank I2 to the settling viding the heat exchanger thus associated with 50 tanks I4 and I6 under pressure. 'I'he liquid pump the circulating system, the heat is removed from 24 may be of any of the well known types and the plating solutionl as it iiows to the settling is adapted to be actuated by means of a motor tanks from the plating tank I2 and is trans-- 26 which is connected to some suitable source ferred to the cooled and purified plating solution 5 of power (not shown). to warm it before it is admitted to the plating 55 l the plating of obJects, valves 58 and 68 tank. Eillcient operation of the purifying apparatus is thus obtained, since the plating solution from the plating tank I2 that is cooled in the heat exchanger may be more easily refrigerated in the settling tanks.

In order to'provide for the cleaning of the circulating system and particularly the settling tanks I4 and I6, provision i's made for supplying flushing uid to the circulating system. The flushing fluid, such as tap water, may be supplied to the circulating system through inlet and removed therefrom through the outlet 52. Valves 54 and 56 are provided in the inlet and outlets 58 and 52, respectively for controlling the admission of the flushing fluid to the circulating system. Valves 58 and 68 are disposed in the supply pipe 22 and return pipe 32, respectively, in the circulating system adjacent to the plating tank I2 for disconnecting the circulating system from the plating tank when it is desired to flush the apparatus to remove the impurities.

In operation, when it is desired to perform are actuated to their closed position to disconnect the plating tank I2 from the circulating system I8. The plating solution is then supplied to the plating tank I2. .After a time interval, it is found that the plating solution in the tank I2 contains impurities which render the plating process inefficient. In employing the apparatus of this invention to remove the impurities from the plating solution the operation is as follows:

One of the settling tanks, say I6, is isolated from the circulating system by actuating the valves 46 and 38 in the outlet 38 and inlet 28, respectively, to their closed position. Valve 36 in the outlet pipe 28 of settling tank I4 is also actuated to its closed position to prevent the flow of uid from the settling tank I4 while valve 34 in the inlet pipe I8 is actuated to its open position to permit the flow of fluid to the settling tank. With the valves in the position as indicated, valve 54 in the inlet pipe 58 is actuated to its open position to permit the flow of a flushing fluid, such as tap water, into the supply pipe 22 lwhere it is forced by means of the liquid pump 24 to flow through the inlet pipe I8 to the settling tank I4. When a suitable amount of flushing uid is in the supply pipe 22 and the settling tank I4, valve 54 is actuated to its closed position to cut oi the supply of the flushing fluid to the supply pipe 22. The pump 24 functions to force the ushing fluid under pressure from the supply pipe 22 into the settling tank I4. After the ushing fluid is forced out of the supply pipe 22 into the settling tank I4, the valve 34 is actuated to its closed position and the flushing uid is refrigerated in the settling tank to lower its temperature to approximately the freezing point of the flushing fluid.

When the temperature of the flushing uid is `reduced to a predetermined value, valve 58 is actuated to its open position to permit the flow of plating solution from the supply pipe 22. Valve 38 in the inlet pipe 2Il is also opened to permit the flow of the plating solution from the supply pipe 22 into settling tank I6. At the same time valve 36 in the outlet pipe 28 of settling tank I4 and valve 56'in the outlet pipe 52 are opened to permit the flow of the flushing fluid from the settling tank I4 out of the circulating system. Liquid pumps 24 and 42 may be actuated to simultaneously effect the flow of the liquids in pipes 22 and 32, respectively, under pressure.

the plating tank into l As the plating solution flows from the plating tank I2 through the heat exchanger, the heat of the plating solution is so transferred from the solution in supply pipe 22 to the refrigerated flushing fluid in pipe 32 that the temperature of the plating solution is loweredk to approximately 60 F. When the ushng fluid is forced out of the circulating system and a predetermined plating solution is forced into are deenergized and the valve 56 in the pipe 52 of the circulating system and valve 36 in the outlet pipe 28 of the settling tank I4 are actuated to their closed position. The plating solution in the settling tank I6 is then refrigerated to approximately 25 F. to cause a crystallization of the impurities in the solution. When the impurities crystallize they settle out of the solution and remain on the bottom and side walls of the settling tank.

After the plating solution in the settling tank I6 is refrigerated, valve 34 in the inlet I8 to settling tank I4 may be actuated to its open position to permit the flow of the impure plating solution from the supply pipe 22 to the settling tank I4 and valve 48 in the outlet pipe 38 of settling tank I6 may be actuated to its open position `to permit the flow of the puried plating solution through the return pipe 32 to the plating tank I2-, it being understood that valve 68 is actuate to its open position after valve 56 is actuated to itsclosed position. The liquid pumps 24 and 42 may then be actuated to force the fluid under pressure through the supply pipe 22 and return pipe 32, respectively.

When a suitable amount of the plating solution is pumped into the supply pipe 22 to fill the settling tank I4, valve 58 may be actuated to its closed position to disconnect the supply pipe 22 from the plating tank I2. After the plating solution in the supply pipe 22 and return pipe 32 is forced into the settling tank I4 and plating tank I2, respectively, the operation of liquid pumps 24 and 42 may be stopped and valve 34 maybe actuated to its closed position to isolate settling the circulating system.

impurities to crystallize out of the plating solution in the settling tanks, the circulating system may be cleaned While one of the settling tanks contains plating solution Without interrupting the refrigeration and purification of the plating solution in the isolated settling tank. The cleaning of thecirculating system may be accomplished by forcing the flushing fluid through the supply pipe 22, settling tank I6 and return pipe 32 to the outlet pipe 52.

After settling tank I6 is thus cleaned, valves 54 and 56 in the inlet and outlet pipes 50 and 52, respectively, from the circulating system may be actuated to their closed position and valves 58 and 60 may be actuated to their open position to .connect the circulating system with the plating tank I2. When the impurities are crystallized and settled out of the solution in the settling tank I4, valve 36 may beA actuated to its open position to permit the flow of the purified plating solution to the plating tank I2 and the impure plating solution may then be supplied to the plating tank I6 after first actuating valve 46 in the outlet pipe 30 of the settling tank I6 to its closed position to prevent the flow of the plating solution from the settling tank. Settling tank I4 may then be cleaned after first settling the valves, as hereinbefore indicated, and then forcing the flushing fluid under pressure through the settling tank.-

This apparatus has proven to be of special benefit in purifying tin plating solutions, since it effectively removes or so lowers the sodium carbonate normally formed in the plating solution during the plating operation that the plating operation may be eiciently and economically per` formed. As operation given hereinbefore, it is seen that this apparatus has a further advantage in that the purified plating solution is returned to the platingtank at nearly the operating temperature of the plating solution. Further, the use of the settling tanks, as hereinbefore described, pery mits the reclaiming of the plating solution during the plating operationlto be continuous Without loss of time in cleaning the settling tanks and without interrupting the purification of the plating solution. y

Although this invention has been described with reference to a particular modification thereof, it is, of course, to be understood that it is not to be limited thereto except insofar as is necessitated by the the appended claims.

I claim as my invention: l. Apparatus for the continuous removal of prior art and the scope of impurities from plating solutions comprising, in

combination, a plating tank for containing the plating solution, a circulating system for the circulation of the plating solution from and to the plating tank, a plurality of settling tanks connected in parallel in the circulating system for receiving the plating solution from the plating tank, means associated with each of the settling tanks for isolating either of them, means associated with the settling tanks for refrigerating the plating solution contained therein to eect the crystallization and settling of impurities from the solution, a heat exchanger associated with the circulating system whereby heat from the plating solution owing from the plating tank is transferred to the plating solution flowing to the plating tank, and means for flushing out the circulating system to remove impurities from the unisolated settling tank without interrupting the refrigeration of the solution in the isolated tank.

2. Apparatus for the continuous removal of impurities from plating solutions comprising, in combination, a plating tank for containing the plating solution, a circulating system for the circulation of the plating solution from and to the plating tank, a plurality of settling tanks connected in parallel in the circulating system for receiving the plating solution from the plating tank, means associated with each of the settling tanks for isolating either of them, means associated with the settling tanks for refrigerating the plating solution contained therein to effect the crystallization and settling of impurities from the solution, a heat exchanger associated with the circulating system whereby heat from the plating solution flowing from the plating tank is transferred to the plating solution flowing to the plating tank. and means forcing a fluid under pressure through the circulating system to remove is evidenced from the description of means associated with the settling system for the clrplating tank, a plurality of settling tanks connectedin parallel in the circulating system for receiving the plating solution from the plating tank, means associated" with each of the settling tanks for isolating either of them, means associated with the settling tanks for refrigerating the plating solution contained therein to effect tle crystallization and settling of impurities from the solution, a heat whereby heat from the plating solution flowing from the plating tank is transferred to the plating solution flowing to the yplating tank, means for disconnecting the circulating system from the plating tank, and means for flushing out the circulating system when it is disconnected from the plating tank to remove impurities from the unisolated settling tank without interrupting the refrigeration of the solution in the isolated settlingv tank.

.plating tank, a plurality of settling tanks connectedin parallel in the circulating system for receiving the plating solution from the plating tank, means associated with each of the settling tanks for isolating either of them, means associated with the settling tanks for refrigerating the plating solution contained therein to eiect the crystallization and settling of impurities from the solution,`a heat exchanger associated with the circulating system whereby heat frm the plating solution flowing from vthe plating tank is transferred to` the plating solution flowing to the plating tank, andmeans for flushing out the circulatlng system to remove impurities from the unisolated settling tank without interrupting the refrigeration of the solution in the isolated tank.

5. Apparatus for the continuous removal of impurities from plating solutions comprising, in combination, a plating tankfor containing the plating solution, a circulating system for the circulation of the plating solution from and to the plating tank, a plurality of settling tanks .connected in parallel in the circulating system for receiving the plating solution from the plating tank, means associated with the circulating system for forcing the plating solution to the settling tanks under pressure, means associated with each of the settling tanks for isolating either of them,

tanks for refrigerating the plating solution contained therein to effect the crystallization and settling of impurities from the solution, means associated with the circulating system for' forcing the purified plating solution under pressure from the settling tanks to the plating tank, a heat exchanger associated with the circulating system whereby heat from the plating solution flowing from the plating tank is transferred to the plating solution owing to the plating tank, and means for flushing out the circulating system kthe unisolated settling tank without interrupting the refrigeration of the solution in the isolated tank. l

to remove impurities from plating tank, means associated with the circulating system for forcing the circulation of the plating solution under pressure from and to the plating tank, a plurality of settling tanks connected in parallel in the circulating system for receiving the plating solution lfrom the plating tank, means associated with each of the settling tanks for isolating either of them, means associated with the settling tanks for refrigerating the plating solution contained therein to elect the crystallization and settling of impurities from the solution, a heat exchanger associated with the circulating system whereby heat from the plating solution flowing from the plating tank is transferred to the plating solution flowing to the plating tank, means for disconnecting the circulating system from the plating tank, and means for flushing out the circulating system when it is disconnected from the plating tank to remove impurities from the unisolated settling tank without interrupting the refrigeration of the solution in the isolated settling tank.

7. Apparatus for the continuous removal of impurities from plating solutions comprising, in combination, a plating tank for containing the' plating solution, a circulating system for the circulation of the plating solution from and to the plating tank, a heat exchanger associated with the circulating system for effecting the transfer of heat from the plating solution withdrawn from the plating tank to the plating solution as it is returned to the plating tank, a plurality of settling tanks associated with the circulating system for receiving the plating solution from the plating tank, means associated with the settling tanks for refrigerating the plating solution to effect the crystallization and settling of impurities from the solution in the settling tanks, a plurality of valves associated with each of the settling tanks for isolating it to prevent the ow of additional plating solution through the settling tank, said plurality of valves disposed to be separately operable to permit withdrawal of the puried plating solution while preventing the admission of impure solution to one of the settling tanks while admitting impure solution to the other settling tanks but preventing its withdrawal, means for disconnecting the circulating system from the plating tank, and means for flushing out the disconnected circulating system while any one of the settling tanks containing the plating solution is isolated to remove the settled impurities from the unisolated settling tank without interrupting the refrigeration of the solution in the isolated tank.

8. Apparatus for the continuous removal of lmpurities from plating solutions "comprising, in combination, a plating tank for containing the plating solution, a circulating system for the cir culation of the plating solution from and to the plating tank, means associated with the circulating system for forcing the circulation of the plating solution under pressure from and to the plating tank, a heat exchanger associated with the circulating system for eiecting the transfer of heat from the plating solution withdrawn from the plating tank to the plating solution as it is returned to the plating tank, a plurality of settling tanks associated with the circulating system for receiving the plating solution from the plating tank, means `associated with the settling tanks for refrigerating the plating solution tol effect thev crystallization and settling of impurities from the solution in the settling tanks, a plurality of valves associated with each of the settling tanks for isolating it to prevent the flow of additional plating solution in the settling tank, said plurality of valves disposed to be separately operable to permit withdrawal of the purified plating solution while preventing the admission of impure solution to one of the settling tanks while admitting impure solution to the other settling tanks but preventing its withdrawal, means for disconnecting the circulating system from the plating tank, and means for ushing out the disconnected circulating system while any one of the settling tanks containing the plating solution is isolated to remove the settled impurities from the unisolated settling tank without interrupting the refrigeration of the solution in the isolated tank.

ROBERT H. TULL. 

